Schopf wanted to understand what kind of microbial organisms these fossils are and if they were advanced or primitive.
Schopf teamed up with John Valley, a geoscience professor from the University of Wisconsin-Madison who has been working for 10 years to refine a technique called secondary ion mass spectroscopy, or SIMS. This device shoots an ion beam on a surface and, in a vacuum, collects and analyzes ejected secondary ions, searching for specific types of isotopes.
The work was painstaking, as the fossils are each only about 10 micrometers wide, meaning eight of them could fit along the width of a human hair.
The team analyzed eleven microfossils and were able to separate the carbon from each fossil into its constituent isotopes and measure their ratios. The results indicated they were “characteristic of biology and metabolic function,” Valley said in a statement.
They found several different types of organisms — “a primitive but diverse group,” Schopf said. Two of the species appeared to have performed a simple form of photosynthesis, another apparently produced methane gas, and two others appear to have consumed methane and used it to build their cell walls.
In short, these fossils represent a “community” that lived together and “were a significant component of Earth’s early biosphere,” the team wrote, and were comprised of primitive photosynthesizers, methane producers, and methane users.